France, Britain and Germany, the European signatories to the 2015 Iran nuclear accord, on Friday expressed deep concern at Tehran's violations of the deal and urged it to cooperate with the U.N. nuclear watchdog. 

"The International Atomic Energy Agency (IAEA) confirmed in its report of September 8 that advanced centrifuges had been installed or were being installed in Natanz. We are deeply concerned by these activities," the European powers said in their first joint statement since an IAEA briefing earlier this week. 

"We continue to support the JCPOA (nuclear accord) and urge Iran to reverse its activities that violate its JCPOA commitments, and to refrain from all further action." 

"We call on Iran to cooperate with the IAEA on all relevant matters," said the statement. 

On Monday the IAEA increased pressure on Iran, saying there is no time to waste in answering its questions, which diplomats say include how traces of uranium were found at a site flagged by Prime Minister Benjamin Netanyahu despite it not being declared to the agency.

Tehran on Wednesday accused the U.S. and Israel of applying "undue pressure" on the IAEA to vet its nuclear program and warned it could be "counterproductive" to its cooperation with the agency. 

Tehran's ambassador to the IAEA, Kazem Gharib Abadi, said statements by Israel and the U.S. could jeopardize Iran's "constructive, timely and proactive cooperation" with the watchdog. 

(With input from Reuters, AFP)